lib/crypto: sha256: Make library API use strongly-typed contexts

Currently the SHA-224 and SHA-256 library functions can be mixed
arbitrarily, even in ways that are incorrect, for example using
sha224_init() and sha256_final().  This is because they operate on the
same structure, sha256_state.

Introduce stronger typing, as I did for SHA-384 and SHA-512.

Also as I did for SHA-384 and SHA-512, use the names *_ctx instead of
*_state.  The *_ctx names have the following small benefits:

- They're shorter.
- They avoid an ambiguity with the compression function state.
- They're consistent with the well-known OpenSSL API.
- Users usually name the variable 'sctx' anyway, which suggests that
  *_ctx would be the more natural name for the actual struct.

Therefore: update the SHA-224 and SHA-256 APIs, implementation, and
calling code accordingly.

In the new structs, also strongly-type the compression function state.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 69fe76fd9233..b835033c65eb 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -751,7 +751,7 @@ int kexec_add_buffer(struct kexec_buf *kbuf)
 /* Calculate and store the digest of segments */
 static int kexec_calculate_store_digests(struct kimage *image)
 {
-	struct sha256_state state;
+	struct sha256_ctx sctx;
 	int ret = 0, i, j, zero_buf_sz, sha_region_sz;
 	size_t nullsz;
 	u8 digest[SHA256_DIGEST_SIZE];
@@ -770,7 +770,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
 	if (!sha_regions)
 		return -ENOMEM;
 
-	sha256_init(&state);
+	sha256_init(&sctx);
 
 	for (j = i = 0; i < image->nr_segments; i++) {
 		struct kexec_segment *ksegment;
@@ -796,7 +796,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
 		if (check_ima_segment_index(image, i))
 			continue;
 
-		sha256_update(&state, ksegment->kbuf, ksegment->bufsz);
+		sha256_update(&sctx, ksegment->kbuf, ksegment->bufsz);
 
 		/*
 		 * Assume rest of the buffer is filled with zero and
@@ -808,7 +808,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
 
 			if (bytes > zero_buf_sz)
 				bytes = zero_buf_sz;
-			sha256_update(&state, zero_buf, bytes);
+			sha256_update(&sctx, zero_buf, bytes);
 			nullsz -= bytes;
 		}
 
@@ -817,7 +817,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
 		j++;
 	}
 
-	sha256_final(&state, digest);
+	sha256_final(&sctx, digest);
 
 	ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
 					     sha_regions, sha_region_sz, 0);